Written and directed by Chris and Paul Weitz - the American film-making duo responsible for "American Pie", it's the perfect star vehicle for Grant, allowing him to finally move away from his usual bumbling, tongue-tied screen persona.

Sporting a wardrobe of designer casual clothes and a stylishly short haircut, he plays Will, a wealthy, single thirtysomething in North London. He doesn't work as such - the royalties from his late father's novelty number one hit provide him with a handsome income - but he's not idle: he buys CDs, watches television, and goes out to lunch ("How do people manage to fit in a full-time job?", he wonders).

Claiming that he has a child in order to make himself more attractive to single mothers, Will meets the troubled 12-year-old Marcus (Hoult), whose own hippy mum Fiona (Collette) has tried to commit suicide...

"About a Boy" may chart its central character's emotional awakening through an unlikely friendship, yet much of its humour derives from Will's profound immaturity: he's a congenital liar who makes inappropriately childish comments in grave situations, with his eyes seemingly glazing over during any "serious" conversation with another adult.

He regards his own life as "the Will Show", not an "ensemble drama", although falling in love with beautiful illustrator Rachel (Weisz) causes him to reassess some of these deeply-held certainties.

The brothers Weitz take few risks in their aesthetic choices: more importantly, they smoothly oversee a procession of humorous scenes, culminating in the improbable sight of Grant rocking out with his electric guitar at the school concert.